This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-285676, filed Oct. 6, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates generally to an injection molding machine, and more particularly to a temperature control apparatus for an injection molding machine, which temperature control apparatus has a temperature management section with a temperature correction function.
In an injection molding machine, an injection molding material is supplied and stored in a molten state, and then the material is injected into a molding die. Thereby, injection molding with a desired shape is carried out. The quality of a product formed by injection molding varies greatly depending on the temperature of the injection molding material. Therefore, the management of temperature of the stored material is very important.
In a conventional injection molding machine, the temperature of the injection molding material is detected by a temperature sensor, and a detection analog output is converted to a digital value by a temperature sense module. The digital value is delivered to a CPU. The CPU prestores, as parameter values, temperature correction values relating to the temperature sense module. The parameters are sent from the CPU to the temperature sense module to correct the output from the temperature sensor. The corrected sensor output is delivered to the CPU, and the temperature control is effected based on a set temperature set by a user.
In general, the temperature sense module is provided on a board different from a board on which the CPU is mounted. In case the temperature sense module has malfunctioned, the board of the module is replaced. However, the parameter values which are equal to temperature correction values are proper to the associated temperature sense module. Thus, in the prior art, if the module board is replaced, the parameter values stored in the CPU-side memory need to be rewritten to confirm to a new temperature sense module. This is time-consuming.
There is another known method in which temperature correction is performed in a temperature sense module by means of circuitry, instead of storing temperature correction values in a CPU-side memory, that is, a temperature correction circuit is built in the temperature sense module. In this method, however, set values in the temperature correction circuits need to be set once again to conform to a new temperature sense module, and this is more time-consuming.
The present invention has been made in consideration of the above circumstances, and its object is to provide a temperature control apparatus for an injection molding machine, which enhances the convenience for users in replacing the board of the temperature sense module.
According to the present invention, there is provided a temperature control apparatus for an injection molding machine, the apparatus comprising: a temperature sensor disposed in a temperature management section of an injection molding machine; a temperature sense module connected to the temperature sensor and outputting a temperature sense signal; and a control section for keeping a temperature of the temperature management section at a set temperature by activating a heater provided in the temperature management section in accordance with a difference between the output from the temperature sense module and the set temperature, wherein the temperature sense module has memory means for storing a temperature correction value proper to the temperature sense module, and the control section includes means for controlling the heater on the basis of the temperature correction value.
With the above structure, a board of an individual temperature sense module is provided with memory means for storing temperature correction values proper to the module. Only by replacing the board, an exact temperature control can be performed, and a temperature control apparatus for an injection molding machine with enhanced convenience can be provided.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.